Question: Simplify the following expression: $k = \dfrac{3}{4t} - \dfrac{6}{5t}$
Explanation: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $4t$ and $5t$ $\lcm(4t, 5t) = 20t$ $ k = \dfrac{5}{5} \cdot \dfrac{3}{4t} - \dfrac{4}{4} \cdot \dfrac{6}{5t} $ $k = \dfrac{15}{20t} - \dfrac{24}{20t}$ $k = \dfrac{15 -24}{20t}$ $k = \dfrac{-9}{20t}$